Abstract: It is described an instrument feeder device (201) for use in an endoscope system, for feeding a medical instrument (202) into a body or withdrawing the medical instrument from the body, the instrument feeding device comprising: a connector (302) for connecting the instrument feeding device (201) to a motor 5 (203) for moving the medical instrument (202) through the instrument feeding device (201); a drive wheel (303) arranged to be rotated by the motor, wherein the drive wheel (303) is positioned on one side of the medical instrument (202), an idler wheel (310) positioned on an opposite side of the medical instrument 10 relative the drive wheel (303), a clutch mechanism adapted to push the idler wheel (310) against the medical instrument (202), the clutch mechanism including a rotary button (1012) connected to a spindle (1111), the spindle including a main part and an eccentric part (1111a) which is arranged offset relative a center line through the main part, 15 wherein the idler wheel is rotatably mounted o